2011 Volume 8 Issue 11 Pages 780-787
This paper describes a design procedure for mm-wave voltage controlled oscillator (VCO), based on large signal behavior of oscillator transconductance. Then, a new structure of LC-VCO is presented, which utilizes a transformer feedback to enhance the transconductance of the core transistors and to cancel the undesired parasitic effects. Using a 0.18-µm RF CMOS technology, the advantage of this VCO is examined by large signal analysis and simulation. The results illustrate improvement of 5dB in phase-noise and 70% in tuning-range, compared to enhanced active gain conventional transformer feedback VCO. Finally, a compact layout for transformer design is proposed.